(a) Technical Field
The present disclosure relates to a gravity sensor (G-sensor) circuit system for a vehicle. More particularly, it relates to a circuit system including a G-sensor used in a vehicle for the measurement of a yaw rate, an acceleration rate, and a road inclination angle, and for the detection of a collision.
(b) Background Art
Generally, a vehicle includes an engine to generate power, a power transmission system to drive the vehicle by converting the power generated by the engine into a rotational force of a wheel, a steering system to change traveling direction of the vehicle, a suspension system to improve ride comfort and steering stability by absorbing an impact applied from a road surface, and a brake system to reduce the speed of the vehicle or stop the vehicle.
The operations of these elements are controlled by various electrical and electronic control units to improve the driving performance, stability, ride comfort and convenience.
As an example, a gravity sensor (G-sensor) mounted on front and rear wheels of the vehicle and generating a signal by detecting the vehicle position is provided in an electronic control unit of the vehicle.
In general, the zero point of the G-sensor is set under the assumption that the vehicle is in a horizontal position and then is changed by the traveling state of the vehicle or the state of the road surface, which results in a change in the measurement value of the G-sensor.
The G-sensor is widely used in a variety of vehicles, which are commercially available or under development at present, such as hybrid vehicles and fuel cell vehicles as well as internal combustion engine vehicles. Although the application of G-sensors varies depending on G-sensitivity, unidirectional/bidirectional type, and the like, the G-sensors are used in a variety of electronic control systems of the vehicle such as an anti-lock braking system (ABS), an electronic stability program (ESP), an electronic control suspension (ECS), an airbag system, and an anti-rolling control system to detect the vehicle's position, an inclination angle, and a collision.
In the above-described application, signals output from the G-sensors are used as an input signal and a reference signal for performing an electronic control logic for the measurement of a yaw rate (using left and right G values), an acceleration rate, an inclination angle (using front and rear G values), and an impact strength, and for the detection of a collision.
In more detail, when the vehicle is restarted after being stopped on a slope (“idle stop & go” in an HEV/“stop & go” in a general vehicle), the anti-rolling control system controls the brake system by determining the inclination angle with reference to a signal of the G-sensor during the stop of the vehicle, thus preventing the vehicle from rolling backwards. Moreover, the signals of the G-sensor are used as a collision signal for inflating an airbag in the airbag system, as a reference signal for turning off a main relay of a high-voltage battery during collision of the hybrid vehicle to prevent an electric shock, and as a signal for calculating a target yaw moment as a safety assessment criterion to be compared with a target yaw rate.
As such, the G-sensor is a very important sensor used in a variety of systems in the vehicle for a variety of purposes, and when a failure or malfunction occurs in the G-sensor or when the measurement value contains an error, it would be fatal to the safety of the vehicle and passengers.
However, the conventional G-sensor has no self-diagnosis function and cannot thus determine whether there is a failure in itself. Moreover, during the initial installation of the G-sensor, during the initial installation of a controller which communicates with the G-sensor for the control operation, or during the update of the controller software, the G-sensor itself cannot offset the zero point (e.g., inclination angle zero-offset). As a result, when the G-sensor with an incorrect zero point is used, it is impossible to output an accurate signal and accurately control the vehicle. Furthermore, since the conventional G-sensor outputs an analog signal which is disadvantageous in terms of noise, it is necessary to improve the accuracy.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.